The present invention relates to a semiconductor laser device.
Conventionally, there has been a can package type semiconductor laser device as shown in FIG. 4. The semiconductor laser device of FIG. 4 has a two-body structure of a stem 102 and a cap 104. The stem 102 has a block portion 103 on which a laser chip 101 is mounted. This block portion 103 serves as a base on which the laser chip 101 is mounted and concurrently plays the role of efficiently transmitting heat generated from the laser chip 101 to the main body of the stem 102 during operating. Moreover, a laser beam emitted from the laser chip 101 goes out via a window 104c of the cap 104. A windowpane 108 is attached to the window 104c. 
In recent years, owing to the trend toward thickness reduction of optical disk drives, optical pickup devices have been required to have a thin configuration, and semiconductor laser devices have been required to be compacted. In concrete, the standard size of packages of the semiconductor laser devices is 5.6 millimeters in diameter at present, but further reduction thereof is required up to 3.5 millimeters or less in diameter.
If the package size is simply reduced so as to downsize the package, the block portion 103 on which the laser chip 101 is mounted becomes elongated as shown in the prior art example of FIG. 4. The reason why the block portion 103 becomes elongated as follows.
In coping with the recent demand for speeding up optical disk drives for write, the laser power has been required to have a high output. In response to this, the size of the laser chip 101 is set to about 0.8 millimeters or more. This is for a reduction in current density and an improvement in heat radiation. Then, the block portion 103 of the stem 102 is required to have a length of 1.0 millimeter or more so as to secure a radius between a lower portion of the block portion 103 and the stem 102. Furthermore, the block portion 103 has the elongated configuration so that the block portion 103 and the cap portion 104 do not interfere with each other.
However, in the aforementioned conventional semiconductor laser device, it is extremely difficult to make the stem by forging since the block portion 103 is elongated. Therefore, it is required to braze the block portion 103 made of for example copper to the stem 102. This causes an disadvantage that the manufacturing cost of the stem 102 increases.
Moreover, when the block portion 103 becomes elongated, heat radiation is worsened, which results in disadvantageous rise in temperature of the laser chip 101 during operation. Consequently, the operating lifetime and the temperature characteristic of the laser chip 101 is deteriorated.